Date: Wed, 28 Oct 2015 13:38:28 -0700 From: Rui Paulo <rpaulo@me.com> To: Ganael Laplanche <ganael.laplanche@corp.ovh.com>, Emmanuel Vadot <manu@bidouilliste.com> Cc: freebsd-hackers@freebsd.org Subject: Re: EFI Variables Message-ID: <1446064708.28809.77.camel@me.com> In-Reply-To: <201510280727.19357.ganael.laplanche@corp.ovh.com> References: <6ce779725aab266bc85e92f0ee2186b6@megadrive.org> <201510280727.19357.ganael.laplanche@corp.ovh.com>
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On Wed, 2015-10-28 at 07:27 +0100, Ganael Laplanche wrote: > On Tuesday, October 27, 2015 07:24:23 PM Emmanuel Vadot wrote: > > Hi Emmanuel, > > > I'm currently hacking around the loader.efi > > Great :) > > > I've also added the list and get command to the not working > > "nvram" > > command. > > I had myself posted a PR to fix that command as well as add a verbose > switch > and the ability to specify a variable name, see : > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=202614 > > > For the "set" subcommand I think that the best way to handle it > > is : > > "nvram set myvar data" -> This will set the variable myvar to > > data with > > the freebsd guid (if there is any) > > > > and > > > > "nvram set myvar guid data" -> This will force the guid to <guid> > > It can be useful to set variables containing *strings*, but will > hardly handle > binary stuff :/ > > I am not sure whether it should be the loader's job to set > variables... I can > think of changing the boot order, but it may be difficult to get it > right by > hand and would probably require an upper-level tool, such as > efibootmgr on > Linux. > > > I'll look tomorrow how to access efivars once the kernel is > > booted so > > we can set some from some userland tool (especially the boot > > related > > one). > > Yes, this is interesting as the current kernel (amd64) does not > provide access > to EFI variables at all. > > 10.x/ia64 provided access to EFI variables through libefi(3) and > io(4). It > should be possible to import that code to other archs too, but you'll > have to > save the entry point to the Runtime Services Tables and maybe set a > Virtual > Address Map too (not sure about that point). > It would be nice to set some EFI variables in the loader, but you can't expect to handle binary data from the loader. Like you said, we need a special tool to change EFI variables on a system already running FreeBSD. -- Rui Paulo
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